Internal-combustion engine



2A SHEETS-SHEET 1 Filed Aug. 25, 1948 Jan. 1, 1952 Filed Aug. 25, 1948WJZ.

W. A. MCMILLAN INTERNAL COMBUSTION ENGINE Patented Jan. l, 1952INTERNAL-CUMBUSTION ENGINE Wallace A. McMillan, Glenham, N. Y., assignorto The Texas Company, New York, N. Y., a corporation of Delaware iApplication August 25,1948, Serial No. 46,020 4 This invention relatesto an internal combustion engine ofthe reciprocating piston typeoperating with fuel injection. More particularly, the invention relatesto an engine of this character wherein a single hydrocarbon oil servesas a medium for the lubricating system'of the engine and then as fuelfor the fuel `injection system; and in a preferred embodimentillustrated. the single hydrocarbon oil serves in order as the cooling Imedium, the lubricating medium and the fuel for the engine.

In the present stage of development of internal combustion engines ofthe'reciprocating piston type for automotive and aeronautical purposes,it is considered necessary to employ separate fuels. lubricants andcooling mediums which are tailormade to serve their respective purposes.In the majority of locations and under normal times, this presents nospecial problem, since sources of supply of the various mediums arereadily availv able. In certain isolated localities. and particularly inabnormal times, such as encountered by the military inwar time, thesupply of separate fuels, lubricating oils and cooling mediums for theinternal combustion engines of mobile mi1i-V tary equipment hasrepresented a serious problem. While there have been scattered proposalsin the past tol employ an intermediate light oil, such as a kerosene, asboth the lubricating medium and fuel of an engine, this has necessitatedsacritice both in lubricating effectiveness and in combustionperformance of the engine.

It is a principal object of the present invention to provide an internalcombustion :engine of the fuel injection type which is capable ofoperating at high lubricating effectiveness and also at high combustioneiiiciency and power level on a single hydrocarbon oil medium. i

A further object of the invention is to provide an internal combustionengine of this type wherein the respective-functions of cooling,lubricating and combustion are satisfied in a highly efficient vmannerby a single hydrocarbon oil medium which flows in order from the coolingsystem to the lubricating system and thence to the fuel supply system ofthe engine.

Other objects and advantages of the present invention will be obviousfrom the following description, the attached drawing and the appendedclaims.

In accordance with the present invention, the high power level andeiiiciency'are attained by operating the engine on the Otto cycle at arelatively high compression ratio and on a relatively heavy hydrocarbonoil. of the character of gas oil 3 Claims. (Cl. 12S- 32) or even lightlubricating oil, by utilizing the non# knocking combustion method andapparatus dis closed in the copending application of Everett M. Barber,Serial No. 10,598, iiled February 25, #1948, now Patent No. 2,484,009dated October 11, 1949. In thisgoperation, fuel is injected intocompressed swirling air within a localized portion of the combustionspace during the latter part of the com pression stroke, the firstincrement of injected fue1 is spark-ignited as soon as combustible fuelvapor-air mixture is formed therefrom to establish a flamefront'travelling counter to the swirling air, and the injection of fuelis continued into additional increments of the swirling compressed airimmediately in advance of the travelling name front, so that additionalcombustible mixture is progressively formed and burned substantially asrapidly as formed to develop the power required on each cycle, whileentirely preventing knock irrespective of the quality of the fuelemployed or the compression ratio used. This permits operation on. theOtto cycle at relativelyl high compression ratios with a heavy oil orfuel, thereby securing the advantages of the Otto cycle efficiency andthe higher power level due to the higher compression ratio, as well assupercharging. Further, in accordance with the present invention, thisheavy hydrocarbon oil is rst supplied to the lubricating system of theengine where it is circulated therein to provide the normal lubricatingrequirements; and a portion of the circulating oil is continuously bledoff to the fuel supply system from where it is forced by the usual fuelinjection pump to the injection nozzles of the engine. In this manner,the medium in the lubricating system of the engine is rather rapidlyconsumed, so that any one quantity of oil does not remain in thelubricating system for suicient time to undergo objectionable oxidationor sludging.

As is well known, both motor oils and heavy duty engine oils employed inthe present day automotive, aeronautical, or diesel driven power plantsare of special additive type to withstand rigorous or heavyduty'lubricating conditions encountered over substantial periods oftime. This means that a wide variety of lubricants must be supplied tomeet the demands of the various mobile types of equipment, not tomention the different types of premium fuels required. The presentinvention obviates the necessity for supplying these various types oflubricants and fuels, and enables the mobile equipment to be operatedsatisfactorily at high power level with the supply of a singlehydrocarbon oil-to the lubricating system and Ithe fuel system inseries. Due to the fact that the oil in the lubricating system israpidly consumed, even gas oils or non-inhibited light lubricating oilsfunction very satisfactorily for the lubricating requirements of theengine.

The present invention also provides a further advantageous feature whichis of benefit in mobile equipment operating under extremes ofatmospheric temperatures or in desert service. This involves the use ofthe single hydrocarbon oil in series, flrst, in the cooling system ofsomewhat enlarged capacity to compensate for the lower heat conductivityof the oil in comparison to water or glycol, then in the lubricatingsystem of the engine, and finally as the fuel in the injection system ofthe engine.

The invention is more particularly illustrated in the drawing wherein:

Fig. 1 is a side elevational view of the engine and appurtenances, withparts broken away and in section to illustrate the construction thereof;

Fig. 2 is a horizontal sectional view through one of the enginecylinders looking upwardly toward the cylinder head, together with apartial sectional view through a fuel pump cylinder supplying the fuelinjection nozzle of said engine cylinder.

Referring to the drawings, the engine I is illustrated as of thefour-cylinder Afour-cycle automotive type; but it is obvious that thisis merely by way of example, and any suitable 7type of fuel injectionengine adapted for aeronautical or other purposes can be utilized. Each'engine cylinder II (Fig. 2) is equipped with the customary coolingjacket I2. A conventional multicylinder fuel injection pump I3 is drivenby cam shaft I4 (Fig. 2) interconnected in conventional manner with theengine crankshaft (not shown) to be driven at one-half engine speed forfourcycle`` operation in conventional manner. Each pumping cylinder offuel pump I3 is provided with a plunger I5 operated by cam I6 carried bycam shaft I4. Fuel is supplied, to the pump by feed line IB which leadsto a manifold formed in the pump block I9, the latter beinginterconnected with intake ports opening into each of the pumpcylinders, the intake ports being under the control of the pump plungersI5 in conventional manner. On the pumping stroke of plunger I5 for acooperating cylinder, fuel is forced through the'injection line 20 tothe fuel injection nozzle 2I of a cooperating cylinder.

As shown more particularly in Fig. 2, each cylinder II is provided withan exhaust valve 22 and an air intake valve 23 equipped with a shroud 24set tangentially of the disc-shaped combustion space 25, so that on theintake stroke of the piston (not shown) air is drawn into the cylinder II in a manner to cause a high velocity air swirl within the combustionspace 25 in the direction of the arrow 26. This air swirl is maintainedduring the succeeding compression stroke of the piston, such that theair swirl at the time of fuel injection may be about 6-8 times the R. P.M. of the engine.

The fuel pump I3 is coordinated with engine operation so as to initiateinjection of fuel into combustion space 25 from nozzle 2I about 'I0-40before top dead center of the compression stroke of the piston in thecooperating cylinder II. As shown, the nozzle 2| is mounted andconstructed to inject a spray 28 tangentially of the combustion space inthe direction of air swirl, so that 4 pressed air moving past the nozzleor one side of the combustion space is impregnated with fuel. Mounted inthe periphery of cylinder II less than 90 of swirling movement, andpreferably about 30, is a spark" plug I0 having electrodes II positionedto be contacted by the outer fringe of the flrst formed increment offuel vapor-air mixture from spray 25 substantially as soon as formed.Each spark plug is connected by lead I2 in a conventional ignitioncircuit containing distributor 33 driven in synchronism with the enginein conventional manner, so as to produce a spark of igniting intensityat electrodes 3| about 4-12 crank angle degrees following the initiationof fuel injection, and at the time the first increment of injected fuelin combustible mixture form contacts the electrodes 3|. This initiatescombustion and produces a flame front extending generally radiallyacross the one side of the combustion space 25, said flame fronttravelling counter to the-direction of air swirl. Injection is continuedfrom nozzle 2| in the spray form 28 on each cycle immediately in advanceof the travelling flame front to delevop the power required, thesucceeding increments of combustible fuel vapor-air mixture being thusformed immediately in advance of the travelling flame front and consumedby combustion substantially as rapidly as formed. For full power orload, it will be understood that injection continues on each cycle for atime equivalent to one complete rotation of the swirling air incombustion space 25, or for about -45 crank angle degrees depending uponthe velocity of air swirl. For intermediate or lower loads, fuelinjection is terminated earlier in the cycle, so that only a portion ofthe swirling air is impregnated and burned, it being understood that thelocalized segments of air which are impregnated are consumed bycombustion before any substantial diffusion takes place, so that thelocalized segments are burned at substantially the fuel-air ratio atwhich they are impregnated. This provides the non-knocking -combustlonoperation of the mentioned Barber ordinarily operated at a compressionratio of about 10:1, and with the timingset to produce the peak pressurerise of Otto cycle combustion slightly after top dead center.

Combustion, therefore, pendent of fuel quality, and any fuel which willproperly vaporize and mix with the swirling air in the extremely shortinterval required for movement between the injection nozzle tip and thespark plug electrodes or the travelling flame front can be employed. Itvhas been determined that a relatively heavy fuel within the gas oilrange can be utilized in this engine without preheating. A lubricatingoil within the conventional motor oil range can be utilized bypreheating the fuel prior to injection to a temperature of the order of20o-300 F., which can readily be accomplished by a conventional type ofelectrical heater mountedv on each of the injection lines 2l. This isnot shown in the drawing, since ordinarily a heater is not required, asheat only a localized portion of the swirling comn rejection tothe oilwill normally provide these is completely inde- 8 temperatures. Alubricating oil within the motor oil range can be utilizedsatisfactorily for starting and normal operations without preheating bymixing the same with a small proportion of a light hydrocarbon fuel',such as isopentane. Therefore, the present invention enables theselection as fuels for the engine of a wide variety of the heavierhydrocarbon oil fractions, in addition to the normal fuels of thegasoline and kerosene range. Where the single medium is employed forlubrication, as well as fuel, or for cooling, lubrication and fuel, itwill be understood that a heavier hydrocarbon of at least the heavykerosene range and which has lubricating properties, is selected. Thecontrol of the initiation of injection and duration of injection inaccordance with load is obtained by rotation of the pump plungers Ilthrough the throttle control (not shown) in conventional manner.

Referring again to Fig. 1, the cooling system of the engine I comprisesradiator 3B having upper and lower headers 36 and 3l` with hoseconnections 3B and 3l, respectively. Lower hose connection 39 leads tothe circulating pump 4I operated by the belt and pulley drive 4I fromcam shaft I4.. the upper pulley of drive 4i also operating the coolingfan 42 in conventional manner. It will be understood that thecirculating pump 40 forces the cooling medium which has passed throughradiator $5 through the cooling jackets i2 and other circulatingpassages of the engine block and thence by hose connection I8 to theupper header 36 ofthe radiator. In accordance with the presentinvention, where a relatively heavy hydrocarbon oil having a highinitial boiling point of the order of 250 Rand above is employed as thecooling medium, a closed cooling system without atmospheric connectionor overflow can be used. The hydrocarbon oil for the multifunctionaloperation of the engine is supplied by gravity, or by suitable pump,from oil tank 44 through line 45 to the upper header 3B to maintain thecooling system at all times filled with the hydrocarbon oil. This offersthe further advantage of insuring proper cooling of the engine withoutattention on the part of the operator and without refilling of theradiator, except as the normal fuel tank of the vehicle becomesexhausted. Furthermore, the use of a heavy hydrocarbon oil with acooling system of the required increased cooling capacity offers thefurther advantage of satisfactory operation under extremes of low andhigh atmospheric temperatures without the necessity of changing from ananti-freeze to water cooling, and enables operation under severeconditions encountered in tropical heat or desert operation withoutserious overheating difficulties.

As further shown in Fig. 1, a bleed line 41 is connected in a drilledbore intersecting one of the circulating passages in the engine blockfor the cooling medium. This bleed line leads to and opens into thelower portion of the sump 48 of crankcase 49, and is under the controlof valve 50 operated by float Si. Consequently, a portion of thehydrocarbon oil in the cooling circulating system is bled off into thecrankcase to maintain the desired level of lubricating medium in thelubrication system of the engine. As this oil is bled off, make-up oilfrom tank 44, of course, flows by line 45 into the cooling system. Thecirculating lubricating system of the engine includes the conventionalengine-driven oil pump 52 withdrawing oil by line 53 from sump 48 and Iforcing the same through line 54 to oil ilter 5l, from where a portionreturns by Icy-pass 58 to the sump. and another portion passes bypressure line 5l to the conventional oil circulating passages of theengine and thence returns to the crankcase in the usual manner. Inaccordance with the present invention, a portion of the oil supplied topressure line 51 is continuously bled off by bleed line under thecontrol of valve il to a fuel reservoir 6 I It will be understood thatline i1 may be an open line or may also be provided with a valve 62, sothat the rate of bleed to the fuel reservoir il can be accuratelyregulated or calibrated by manipulation of valve 60, or by both valvesGU and 82. Consequently, a portion of the oil in the lubricating systemis continuously removed to the fuel system during operation of theengine, with make-up oil for the lubricating system being supplied underthe control of the float operated valve Il. Where a lighter hydrocarbonfuel, such as. for example, isopentane or -light aviation or motorgasoline, is to be mixed with the bled off oil, particularly where alubricating oil is supplied to tank 44, a separate fuel tank B3 isprovided and connected by line 64 under the control of valve 65 with thereservoir 6|, which then functions as a mixing tank. It will beunderstood that valves 65 and 6l or 86, 60 and B2 can be provided withsuitable inter-connections with the throttle, so that the rate of bleedfrom thelubricating system to the fuel system, as well as the rate ofsupply of lighter fuel from tank 63, to the reservoir 8| can be inaccordance with the load and fuel requirements of the engine; Or, in thealternative. valves G and 65 can be manipulated by a float control inreservoir 6I. It will be understood that valve `65A can be disconnectedfrom the throttle interconnections, `and kept completely closed whentheoil from tank 44' furnishes the entire fuelrequirements ofr theengine.

Thus, in the particular-.embodiment illustrated, `a singlehydrocarbonoil furnishes the medium for cooling, `lubricating andfueling the engine. This provides notonlythe `advantages for operation`under extremescfjtemperature for the cooling on above, 'but alsoaffords simiu ,Y llubricating system. Thus, a gas oil which `is consumedrapidly in the lubrieating system andfconsequently replaced with freshoil, possesses adequate lubricating properties for even heavy dutyservice and under the extremes of temperature encountered. A lubricatingsystem of the so-called` dry sump type, which contains a relativelysmall quantity of oil for a given enginesize, is particularly suitablefor purposes of the present engine. While the present invention4 is ofparticular utility under exceptional or emergency conditions where thesupply of a single medium for the mobile equipment is highlyadvantageous or necessary, its use is not limited to such exceptionaloperations.

Even where thereis no problem of supply, the present invention offersadvantages particularly in connection with the `modification where thehydrocarbon oil is supplied first tothe lubricating system and then thefuelsystem. In such case, it will be understood that oil tank 44 isconnected by line 45 directly to the iioat operatedvalve" lli in theline leading to sump 48, and the cooling system of the engine isentirely independent and of conventional character. Where waterisreadily available, and the extremes of temperature are notencountered, this modification offers similar advantages from thestandpoint ofsupply. But, in addition, the present invention enables thesocalled heavy duty or additivetype of lubricants to accom:

7- b'eliminated and adequate lubrication. still secured. It isrecognized that the oxidation of lubricating oils with the resultantformation of sludge, increase in neutralization number of the oil, anddeposition of varnish or lacquer on the cylinder walls and pistons,together with serious bearing corrosion, involves a time factor. Duringthe first few hours of engine operation under severe test conditions,the oxidation or deterioration of the oil is relatively slight. However,as the test is prolonged beyond this so-called induction period, andoxidation starts with increase'ln neutralization number, the rate ofdeterioration of the oil then progressively increases to a maximum.These test conditions, of course, involve operation which is equivalentto 500 to -1,000

miles of automotive service, for example, and thus represent theprolonged period of service of the lubricating oils as conventionallyemployed.

The present invention involves a new approach to the lubricant problem,and enables aturnover of the medium in the lubricating system in arelatively short period of time, equivalent, for example, to about -200miles of operation. Consequently, the lubricant is replaced beforesubstantial oxidation reactions set in under normal conditions ofservice. Moreover, by the use of specially refined gas oils which aremore resistant to these oxidation reactions than the heavier lubricatingoils, the lubricant is replaced in the system before any substantialoxidation and sludging occurs. The net result is that substantially theonly type of impurity getting into the lubricating medium under theseconditions is combustion soot resulting from blow-by; and the latter isreadily removed by the conventional oil filter 55. Consequently, boththe lubricant and fuel systems are maintained relatively free fromimpurities of the character of sludge; and the only requirement is formore frequent replacement of the oil filter 55 which is a simple andinexpensive matter.

While the use of the gas oil type of multifunctional medium is preferredfor the present invention, the conventional types of lubricating oilsare not excluded. As pointed out above, these can be employed alone asfuel; or a light hydrocarbon fuel can be blended with the lubricatingoil prior 'to injection. Moreover, while the additive types oflubricants are normally not required, these can also be used where theadditive is of such character as to avoid precipitation in the injectionlines and nozzles, or where the additive is not precipitated byadmixture with lighter fuels when the latter are employed. A verysatisfactory type of multi-functional hydrocarbon oil for purposes ofthe present invention is a gas oil having a boiling range of about40G-700 F.

Obviously many modifications and variations of the invention as aboveset forth may be made without departing from the spirit and scopethereof, and therefore, only such limitations should be imposed as areindicated in the appended claims.

I claim:

1. The method in the operation of an internal combustion engine of thereciprocating piston type Awhich comprises supplying a hydrocarbon oilhaving lubricating properties to the cooling system of the engine andcirculating the same therein, bleeding off a portion of the circulatinghydrocarbon oil in liquid state from the cooling system-and supplying itto the lubrication system of the engine and circulating the .sameina-the latter, bleeding'off a, portion of the circulating hydrocarbonoil in liquid'state from the said lubrication system and then injectingthe bled off hydrocarbon oil into compressed air within the combustionspace of a cylinder of said engine to provide for combustion therein todevelop the power required, whereby the said hydrocarbon oil provides inorder the cooling, lubricating and fuel requirements of the engine, andintroducing fresh hydrocarbon oil into said cooling system to make upfor that bled off. v

2. In an internal combustion engine of the reciprocating piston type,the combination with the crank case and circulating lubricatingsystem ofsaid engine, of.a lubricating oil tank, means including a flow line forsupplying lubricating oil from said tank to said crank case and tomaintain a constant level of lubricating oil therein, an offtake from.said crankcase'below the. lubricating oil leveltherein, an oil pumphaving its suction side connected to said offtake, a vdividedline-connected to lthe pressure side .of said oil pump, a by-pass linealso connected to the pressure side of said pump and leading to saidcrankcase to return excess lubricating oil directly to the latter, oneportion of said divided line being connected to said engine circulatinglubricating system, a mixing tank, the other portion of said dividedline being a bleed line connected to said mixing tank through a controlvalve to supply lubricating oilto -the mixing tank, a fuel tank, a valvecontrolled line connecting ,said fuel tank with saidmixing tank tosupply liquid tothe latter, a fuel pump, a fuel injectorfor said engineconnected to the pressure side of said fuel pump, and a line connectingthe suction side of said fuel pump with said mixing tank.

3. In an internal combustion engineof the reciprocating piston type, thecombination with a circulating cooling lsystem for said engine, of acirculating lubricating system for said engine, a valve controlled bleedline for bleeding off a portion of the circulating medium in saidcooling system in liquid state to said lubricating system, a fuelinjection system for said engine, a valve controlled bleed line fromsaid circulating lubricating systemto said fuel injection system.whereby the same medium passes in liquid state in order fromsaid'cooling system to said vlubricating system and thence to said fuelinjection system to serve as Vthe fuel in the latter, and an oil supplytank connected to said ycooling system to supply `make-up mediumto thelatter.

WALLACE A. MCMILLAN.

REFERENCES CITE) The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 830,144 Frantz Sept. 4. 19061,480,402 Krollage Jan. 8, 1924 2,066,452 Bernard Jan. 5, 1937 2,319,858Grow May 25. 1943 FOREIGN PATENTS Number Country Date 792,405 FranceOct. 21, 1935

